JPH10288863A - Electrostatic charge image developing yellow toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic charge image developing yellow toner that hardly generates emit odor when it is used. SOLUTION: This yellow toner is prepared by kneading a disazo pigment with at least a binder resin and controlling a content of amines to <=20 ppm. The disazo pigment is prepared by causing a tetrazopbenzidine solution to react with a coupler solution containing a stoichiometrically excessive amount of acetoanilides to the benzidines and adding a hypoiodite to the obtained disazo pigment slurry to decompose the excess of acetoanilides into an NH3 gas and water-soluble organic matter and to reduce amounts of acetoanilides in the pigment and aromatic amines derived from acetoanilides.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a yellow toner used for developing an electrostatic latent image in electrophotography, electrostatic recording, and electrostatic printing.

[0002]

2. Description of the Related Art An electrophotographic method is disclosed in U.S. Pat.
No. 7,691, JP-B-42-23910, etc. are known, but an electrostatic latent image is formed on a photoreceptor by various means using a photoconductive substance, and the latent image is formed. The image is developed with a developer, the toner powder image is transferred to a transfer material such as paper, and then fixed by heating, pressure, heating and pressurizing, or solvent vapor to obtain a copy. In addition, a cleaning step for removing the residual developer is usually provided. A developing method for visualizing an electrostatic latent image is described, for example, in US Pat.
No. 63, No. 2, 6
A cascade development method described in JP-A-18-522 and a method using a conductive magnetic developer described in JP-A-3,909,258 are known. As a developer applied to these developing methods, a fine powder in which a dye or a pigment is dispersed in a natural or synthetic resin is conventionally used. For example, particles obtained by dispersing a colorant in a binder resin such as polyester and pulverized to about 1 to 20 μm are used as a developer. When a two-component developer is used, the developer is usually used by being mixed with carrier particles such as iron powder. In recent years, such recording methods have been widely used not only for general copying machines but also for computer output, so that the required performance has become higher, and miniaturization, weight reduction, lower energy consumption, and maintenance have been achieved. Various demands have been made, such as for free. In order to satisfy these demands, demands on developers have been increasing year by year.

[0003] Disazo pigments are useful yellow pigments widely used in the fields of inks, paints and the like as well as toners for developing electrostatic images (hereinafter abbreviated as toners).
Such disazo pigments are obtained by performing a coupling reaction between a tetrazo component of benzidines and an acetoacetanilide called a coupler. The coupling reaction is performed by injecting an aqueous tetrazo solution into a weakly acidic aqueous slurry in which coupler particles are dispersed.
The tetrazo component is chemically unstable and easily decomposes and condenses. This tendency is remarkable especially on the alkaline side and decomposes immediately. Although it is quite stable by strong acidification, the coupling reaction hardly proceeds in this region. For this reason, the coupling reaction is carried out under weak acidity and under such conditions that all the injected tetrazos immediately react with the coupler.

[0004] On the other hand, the coupler dissolves well on the alkali side, but has a considerably poor solubility under weak acidity where the coupling reaction is carried out, and mostly exists as a solid. Therefore, the coupling reaction is performed as a solid-liquid reaction in which a tetrazo solution is injected into a weakly acidic aqueous slurry in which coupler particles are dispersed. For this reason, if the dissolution of the coupler is insufficient for some reason, a high reaction rate often cannot be obtained.

The conversion of the coupling reaction can be improved by finely dispersing the coupler in the aqueous slurry. Various measures are taken to adjust the coupler particles. For example, a coupler dissolved in an alkaline aqueous solution is poured into an acid aqueous solution to cause re-precipitation to be finely divided, or a sand mill or the like is used to mechanically pulverize and refine the fineness.

[0006] In the early stage of the coupling step, it is considered that the coupler in the dissolved state and the tetrazo component are coupled. However, as the coupling proceeds, the dissolution of the coupler cannot be made in time, and the reaction occurs near the surface of the coupler particles. Also, even if the supply of the tetrazo component is too fast,
Alternatively, the same phenomenon occurs when the coupling reaction between the tetrazo component and the coupler is too fast. When such a phenomenon occurs, the produced pigment covers the surface of the coupler particle, and hinders dissolution of the coupler or hinders the coupling reaction. It is thought that at the end of the coupling reaction, the couplers that are thus coated with the pigment and cannot be coupled remain, thereby lowering the reaction rate. Therefore, in addition to miniaturizing the coupler as described above in order to improve the reaction rate, the tetrazo component is stoichiometrically approached to the coupler, the tetrazo component is slowly injected, or the coupler particles coated with the pigment are mechanically Various methods such as forced dissolution by a method or a method of adding a solvent or the like have been proposed, but it is difficult to sufficiently improve the reaction rate in these methods, and unreacted in the resulting pigment The coupler tends to remain. Or it may take a long time to get a sufficient reaction rate,
It was not satisfactory in terms of productivity.

[0007] It has also been described above that the residual amount of the coupler component can be reduced by bringing the tetrazo component and the coupler component closer to the stoichiometric amount and slowly injecting the tetrazo component to reduce the residual amount of the coupler component. In such a case, the tetrazo component tends to remain on the contrary, and the decomposition product derived from the tetrazo component stains the hue of the pigment, and when such a pigment is used, there is a problem that the sharpness of a printed matter or the like is significantly reduced.

As a method for reducing the residual coupler, that is, the residual acetoacetanilide, an alkali is added to the pigment slurry after the coupling reaction to dissolve the residual acetoacetanilide, and excess acetoacetanilide is removed at the time of filtering the pigment. Although there is a method of removing the acetoacetanilide together with the filtrate, excess acetoacetanilide tends to be occluded in the pigment particles, and it has been difficult to sufficiently remove the residual acetoacetanilide.

[0009] Unlike ordinary paints and inks, toners require that pigments be dispersed at a considerably high temperature during production. Specifically, the toner is generally obtained by melt-kneading a colorant such as a pigment and a binder resin, cooling, pulverizing, and classifying as necessary.However, conventionally, an unpleasant odor is generated when the disazo pigment is melt-kneaded. Sometimes happened. In the electrophotographic method, toner is attached to an electrostatic latent image on a photoreceptor or the like, the visualized image is transferred onto a transfer material such as paper, and then heated to fix the transferred image, and image / character information is transferred. However, unpleasant odors may be generated even during such actual use, and it is desired to suppress or prevent the generation of unpleasant odors.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a yellow toner for developing an electrostatic charge image which is less likely to cause odor during use.

[0011]

Means for Solving the Problems The present inventors have conducted intensive studies on the odor generated when using a yellow toner containing a disazo pigment, and as a result, the residual coupler in the disazo pigment used was attributed to the cause of the odor. Is partially decomposed by heat at the time of melt-kneading or toner fixing, and turns into aromatic amines with an unpleasant odor, and is a disazo pigment containing residual couplers and reducing aromatic amines derived from residual couplers. The present invention has been achieved by using.

That is, the first invention provides a disazo pigment (1)
And at least a binder resin by melt-kneading, wherein the content of amines is 20 ppm or less.

According to a second aspect of the present invention, the disazo pigment (1) is subjected to a coupling reaction between a tetrazo solution of benzidine and a coupler solution containing a stoichiometric excess of acetoacetanilide relative to the benzidine. To the resulting disazo pigment slurry, add hypoiodite and then adjust the pH
The yellow toner for developing an electrostatic image according to the first invention, wherein the yellow toner is prepared to 5.5 or less, and an excess acetoacetanilide is treated with precipitated iodine.

According to a third aspect of the present invention, the disazo pigment (1) is prepared by treating excess acetoacetanilides with precipitated iodine, and then adding and kneading a water-soluble inorganic salt and a water-soluble solvent without going through a drying step. The yellow toner for developing an electrostatic image according to the second invention, which is a treated disazo pigment (3) obtained by removing the water-soluble inorganic salt and the water-soluble solvent later.

In a fourth aspect of the present invention, the disazo pigment (1) is prepared by treating an excess acetoacetanilide with precipitated iodine, passing through a drying step, adding a water-soluble inorganic salt and a water-soluble solvent, and kneading the mixture. The yellow toner for developing an electrostatic image according to the second invention, which is a treated disazo pigment (4) obtained by removing the water-soluble inorganic salt and the water-soluble solvent.

According to a fifth aspect of the invention, there is provided a disazo pigment (3) or (4) after removing the water-soluble inorganic salt and the water-soluble solvent.
Image development according to the third or fourth invention, characterized in that a mixture of water and water is heated and kneaded together with a dispersing resin, water is removed, a binder resin is added, and the mixture is melted and kneaded. Yellow toner.

According to a sixth aspect, the disazo pigment (3) or (4) is obtained after removing the water-soluble inorganic salt and the water-soluble solvent.
The yellow toner for developing electrostatic images according to the third or fourth invention, characterized in that a mixture of water and water is kneaded with a binder resin by heating and kneading to remove water.

The seventh invention is characterized in that the water-soluble inorganic salt and the water-soluble solvent are removed, dried, and then heated and kneaded together with the disazo pigment (3) or (4) and a binder resin. The yellow toner for developing an electrostatic image according to the third or fourth aspect of the invention.

The eighth invention relates to disazo pigments (1) to
(4) the static particle according to any one of the first to seventh inventions, wherein the average particle size is 0.3 μm or less, and the ratio of the major axis to the minor axis of the pigment particles is 3.0 or less. This is a yellow toner for developing a charge image.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The disazo pigment (1) used in the present invention is a coupling reaction between a tetrazo solution of benzidine and a coupler solution containing a stoichiometric excess of acetoacetanilide relative to the benzidine. Hypoiodite is added to the disazo pigment slurry obtained by the reaction, and the pH is adjusted to 5.5 or less. Excess acetoacetanilides are decomposed into NH ₃ gas and water-soluble organic substances by the precipitated iodine. By doing so, acetoacetanilides and aromatic amines derived from the acetoacetanilides in the pigment are reduced.

The benzidines used as the tetrazo component in the present invention include 3,3'-dichlorobenzidine, 2,2 ', 5,5'-tetrachlorobenzidine, 3,3'-dimethoxybenzidine and the like. .

The acetoacetanilide used as a coupler in the present invention includes acetoacetanilide, acetoaceto-o-toluidide, acetoaceto-
m-Xylidide, acetoaceto-o-anisidide, acetoaceto-2,5-dimethoxyanilide, acetoaceto-p-anisidide, acetoaceto-2,5-dimethoxy-4-chloroanilide, acetoaceto-o-chloroanilide and the like.

The coupling method may be a conventionally known method, and the above coupler is used in stoichiometric excess with respect to the tetrazo component. For example, it is preferable to use an excess amount up to 15 mol%.

An aqueous solution of hypoiodite is added to the disazo pigment slurry obtained by the coupling, and the pH of the slurry is adjusted to pH5.
The pH is adjusted to 5 or less, preferably pH 3.8 to 5.0, and heating is performed. Hypoiodite aqueous solution contains iodine and alkaline substances,
In particular, it can be obtained by reacting an alkali metal hydroxide in water. The amount of iodine at this time is 0.1 to 20% by weight of the pigment, preferably 1 to 10% by weight. Examples of the alkali metal hydroxide include sodium hydroxide and potassium hydroxide. The amount of the alkali metal hydroxide is preferably 2 to 50 moles, more preferably 3 to 10 moles of iodine. The heating time is not particularly limited, but 25 to 100 ° C,
Preferably it is 30-90 degreeC. The heating time is preferably from 30 minutes to 2 hours.

As described above, the purpose of first converting iodine to an aqueous solution of hypoiodite and then acidifying it to precipitate iodine is to remove residual couplers and their decomposed products in the disazo pigment slurry, especially aromatic amines. Therefore, iodine can be made to act more effectively. Iodine not only has low solubility in water, but its commercial product is a coarse plate-like crystal, so that the dissolution rate is further reduced. On the other hand, the re-precipitated iodine according to the present invention becomes about 10 ^-4 times fine particles of a commercial product, and the dissolution rate is greatly increased. Compared to treatment with mere alkali, treatment with reprecipitated iodine allows the iodine to penetrate into the pigment particles more easily, so that the coupler incorporated into the pigment particles is more effectively treated and contains aromatic amines. It is considered that the amount could be reduced.

The amount of the alkali metal hydroxide used when converting iodine to hypoiodite must be at least twice the amount of iodine at room temperature. Further, the change from hypoiodite to iodine starts from pH 5.5 to 5.0,
Complete in 4.0-3.5. The pigment slurry after the treatment with the reprecipitated iodine is filtered and washed with water to remove the water-soluble organic matter derived from the coupler generated in the treatment, thereby obtaining the disazo pigment (1) used in the present invention.

The disazo pigment (1) preferably has an amine content of 125 ppm or less.
pm or less. The amines in the present invention are acetoacetanilides as couplers and decomposition products of the acetoacetanilides.

In the present invention, a water-soluble inorganic salt and a water-soluble solvent are added to a non-dried disazo pigment or a dried once-disazo pigment after treatment with reprecipitated iodine and filtration and washing with water. A so-called salt milling-processed fine disazo pigment obtained by removing the water-soluble inorganic salt and the water-soluble solvent after kneading (3)
(4) can also be used.

Salt milling refers to a method in which inorganic particles are used as a grinding aid and a water-soluble solvent is used to mechanically make the primary particles of an organic pigment fine. Add a small amount of water-soluble solvent to the mixture of inorganic salts, knead strongly with a kneader, etc., then put the kneaded material in water to dissolve the water-soluble inorganic salt and water-soluble solvent to form a slurry,
Next, the slurry is repeatedly filtered and washed with water to remove the inorganic salt and the solvent and to refine the pigment.

Examples of the water-soluble inorganic salt used in the salt milling treatment include salt, potassium chloride, sodium sulfate and the like. The amount of the water-soluble inorganic salt used is 2 to 20 times, more preferably 3 to 10 times the weight ratio of the water-soluble solvent.

The water-soluble solvent used in the salt milling treatment in the present invention is not particularly limited as long as it is water-soluble, but it is preferable to use a solvent having a high boiling point in order to make the solvent difficult to evaporate. The water-soluble solvent is added for a binder and an effect of preventing crystallization. For example, 2-
(Methoxymethoxy) ethanol, 2-butoxyethanol, 2- (isopentyloxy) ethanol, 2-
(Hexyloxy) ethanol, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monomethyl ether, liquid polyethylene glycol, 1-methoxy-2-propanol,
1-ethoxy-2-propanol, 1-ethoxy-2-
Propanol, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, low molecular weight polypropylene glycol and the like are used. The amount of the water-soluble solvent used is preferably 2 to 10 times by weight based on the disazo pigment to be treated.

In addition to the above compounds, additives such as a dispersant and a plasticizer may be used in combination during salt milling, or two or more pigments may be mixed and treated.

In the present invention, the disazo pigment (3) or (4) that has been subjected to the salt milling treatment as described above is filtered and washed with water according to a conventional method to remove the inorganic salts and the solvent, and then dried. May be melt-kneaded with a binder resin described later, or may be a disazo pigment (3) or (4) without drying after removing the inorganic salt and the solvent.
A mixture of disazo pigment (3) or (4) and water may be melt-kneaded with a binder resin together with a binder resin, or may be dried without removing an inorganic salt and a solvent. The disazo pigment (3) or (4) is transferred to the dispersing resin by applying a mechanical shearing force together with the resin and kneading, and the surface of the disazo pigment (3) or (4) is coated with the dispersing resin. Then, water is removed to obtain a resin-dispersed disazo pigment, and the resin-dispersed disazo pigment can be melt-kneaded with a binder resin to obtain a toner. Is most preferred.

As the dispersing resin used in the case of the third method, a resin similar to a binder resin described later may be used, or a resin of another system may be used. When a resin of a different system from the binder resin is used, it is preferable to use a resin having high compatibility with the binder resin in order to highly disperse the pigment, and examples thereof include a polyester-based resin, a styrene-acryl-based resin, and an epoxy-based resin. be able to. Such a method is preferably performed under heating in order to ensure an affinity between the resin for dispersion and the salt milling-treated organic pigment. In this step, it is possible to use an organic solvent, but if an organic solvent is used in combination, it is preferable that the heating temperature is set to be equal to or lower than the boiling point of the organic solvent to be used so that the solvent is not easily evaporated. . This is because if the solvent evaporates due to heat, the pigment fine particles agglomerate, resulting in poor transparency and coloring. However, it is preferable to use only water from the viewpoint of energy cost and environmental conservation without requiring an organic solvent recovery step.

In the step of kneading the mixture of the disazo pigment (3) or (4) and water together with the dispersing resin by applying a mechanical shearing force, a phthalocyanine pigment derivative, a polymer type dispersant, etc. A dispersing aid may be added.

In the present invention, as a device for applying a mechanical shearing force, a kneader, a pressure kneader, a three-roller, an extruder, a mixing / kneading mixer having a plurality of high-speed rotating stirring blades represented by a Henschel mixer, and the like are used. Can be mentioned.

In the present invention, a method of removing water after kneading a mixture of the disazo pigment (3) or (4) and water together with a dispersing resin by applying a mechanical shearing force, and In addition to a typical drying method, a three-roll roll or the like may be used if necessary.

The average particle size of the disazo pigment obtained by the above-mentioned various methods and used in the present invention is 0.3 μm.
Or less, more preferably 0.2 μm or less. The toner using such a pigment is OHP
An image having excellent transparency and sharpness can be formed on a sheet. Further, the ratio of the major axis to the minor axis of the pigment particles, that is, the so-called aspect ratio, is preferably 3.0 or less. The aspect ratio of the disazo pigment used in the present invention is preferably 3.0 or less, more preferably 2.0 or less. When the aspect ratio is larger than 3.0, the pigment is needle-like and thus is easily exposed from the toner surface, and is easily affected by the external environment.

The yellow toner for developing an electrostatic image of the present invention contains at least a binder resin and the above-mentioned disazo pigment. The binder resin and the disazo pigment are preliminarily mixed and then melt-kneaded with an extruder. The particles can be obtained by pulverizing and classifying so-called base toner particles, and further mixing an external additive as necessary with the base toner particles.
The mother toner for a yellow toner for developing an electrostatic image of the present invention preferably contains 1 to 10% by weight of a disazo pigment. When the amount is less than the above range, the image density is reduced, and when the amount is more than the above range, the chargeability is reduced and fog is caused. The base toner particles may contain a known charge control agent such as a metal salt of a salicylic acid derivative or a polymer type quaternary ammonium salt. As the external additive, a hydrophobic metal oxide or the like may be used. And other known additives can be used.

As the binder resin used in the present invention, a non-linear resin having a good fixing property, for example, a polyester resin, an acrylic resin, a styrene-acrylic resin, an epoxy resin or the like can be used. Particularly preferred is a polyester resin,
The diol component may be a bisphenol derivative represented by a bisphenol A-alkylene oxide adduct or a substituted derivative thereof alone or in combination with an aliphatic dialcohol, and these diol components and a divalent or higher carboxylic acid, for example, What condensed or co-condensed with carboxylic acid components, such as fumaric acid, terephthalic acid, and trimellitic acid, is used suitably.

[0041]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. In the examples, “parts” or “%” indicates “parts by weight” or “% by weight”. Synthesis Example 1 30 parts of 35% hydrochloric acid and 600 parts of ice water
25.3 parts of 3'-dichlorobenzidine are added, followed by
13.8 parts of sodium nitrite were added to form a tetrazo solution to obtain a tetrazo solution. On the other hand, 17 parts of sodium hydroxide and 42.0 parts of acetoaceto-m-xylidide were added to 300 parts of water.
At 0 ° C., an alkaline solution of the coupler was prepared. Water 600
After adding 22 parts of 80% acetic acid to the mixture, the alkali solution of the coupler was dropped, and the coupler was acid-precipitated to prepare a submersion solution. A tetrazo solution was poured into the submersion solution from below the liquid level for coupling. I let it. Add iodine 3 to the obtained pigment slurry.
The mixture was added with a sodium hypoiodite solution formed by mixing 2 parts of sodium hydroxide and 2 parts of sodium hydroxide and 40 parts of water, adjusted to pH 4.0 using hydrochloric acid, and heated to 80 ° C. After leaving for 60 minutes,
This slurry was filtered, washed with water and dried to obtain a disazo pigment (CI Pigment Yellow 13).

Synthesis Example 2 A coupling reaction was carried out in the same manner as in Synthesis Example 1 except that acetoaceto-o-toluidide was used, and 1 part of iodine, 1 part of sodium hydroxide and 15 parts of water were used.
After adding a sodium hypoiodite solution produced by mixing the parts, the mixture was adjusted to pH 3.6 with hydrochloric acid and heated to 90 ° C. After standing for 60 minutes, the slurry was filtered, washed with water and dried to obtain a disazo pigment (CI Pigment Yellow 14). [Synthesis Example 3] Acetoaceto-2,5-dimethoxy-4-
A coupling reaction is performed in the same manner as in Synthesis Example 1 except that 57.0 parts of chloroanilide is used, and a sodium hypoiodite solution produced by mixing 8 parts of iodine, 6 parts of sodium hydroxide, and 120 parts of water is added. Thereafter, the pH is adjusted to pH 4 using hydrochloric acid.
It was set to 0 and heated to 70 ° C. After standing for 60 minutes, the slurry was filtered, washed with water and dried to obtain a disazo pigment (C.I.
I. Pigment Yellow 83) was obtained.

Synthesis Example 4 A coupling reaction was carried out in the same manner as in Synthesis Example 1 except that acetoaceto-o-anisidide was used, and 2 parts of iodine, 2 parts of sodium hydroxide, and 30 parts of water were used.
After adding a sodium hypoiodite solution formed by mixing the parts, the mixture was adjusted to pH 3.8 with hydrochloric acid and heated to 80 ° C. After standing for 90 minutes, the slurry was filtered, washed with water and dried to obtain a disazo pigment (CI Pigment Yellow 17).

[Comparative Synthesis Example 1] The pigment slurry after the coupling in Synthesis Example 1 was heated to 30 ° C, left for 60 minutes, filtered, washed with water and dried to obtain a pigment.

[Comparative Synthesis Example 2] The pigment slurry after the coupling in Synthesis Example 2 was heated to 90 ° C, left for 60 minutes, filtered, washed with water and dried to obtain a pigment.

[Comparative Synthesis Example 3] The pigment slurry after the coupling in Synthesis Example 4 was heated to 80 ° C, left for 90 minutes, and then filtered, washed with water and dried to obtain a pigment. .

Example 1 Non-Linear Polyester Resin 100 parts Pigment of Synthesis Example 1 (CI Pigment Yellow 13) 8 parts The above-mentioned raw materials were mixed with a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.) and extruded. And then pulverized and classified to obtain yellow toner particles. The volume average particle size of the obtained yellow toner particles was measured using a Coulter counter (TA-I
It was 8.5 μm as determined in I). 0.6% of anatase-type titanium oxide fine particles subjected to a hydrophobic treatment were added to the yellow toner particles to obtain a yellow toner.

[Examples 2 to 3] Using the pigments of Synthesis Examples 2 and 3 in the same manner as in Example 1, a yellow toner was produced.

Example 4 Disazo pigment obtained in Synthesis Example 4 (CI Pigment Yellow 17): 250
Parts, sodium chloride: 1000 parts, and diethylene glycol 200 parts (manufactured by Tokyo Chemical Industry Co., Ltd.) were charged into a stainless 1-gallon kneader (manufactured by Inoue Seisakusho) and kneaded for 3 hours.
Next, the mixture was poured into 2.5 liters of warm water, heated to about 80 ° C., and stirred. After stirring for about 1 hour to form a slurry, filtration and washing with water were repeated 5 times to remove sodium chloride and the solvent, thereby obtaining a mixture of a disazo pigment having a solid content of 50% and water. When the form of the pigment in the mixture was observed with a transmission electron microscope, the average particle size was 0.09 μm.
m, the ratio of the major axis to the minor axis of the pigment particles was 1.3.

Next, the following materials were placed in a super mixer (manufactured by Kawata Corporation), heated and kneaded at 80 ° C., and water was removed to prepare a resin-dispersed disazo pigment. Mixture of the above disazo pigment and water (solid content 50%) 100 parts Linear polyester resin 50 parts Polymeric dispersant 2.5 parts

The following materials were mixed with a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.), melted and kneaded with an extruder, pulverized and classified to obtain yellow toner particles. 94 parts of non-linear polyester resin 6 parts of resin-dispersed disazo pigment (CI Pigment Yellow 17) 6 parts The volume average particle diameter of the obtained yellow toner particles was determined by a Coulter counter (TA-II). It was 5 μm. 0.6% of anatase-type titanium oxide fine particles subjected to a hydrophobic treatment were added to the yellow toner particles to obtain a yellow toner.

Comparative Examples 1 to 3 Toners were obtained in the same manner as in Example 1 except that the pigments of Comparative Synthetic Examples 1 to 3 were used instead of Synthetic Examples 1 to 3.

(Quantitative determination of amines) The disazo pigment obtained in each of the above Synthesis Examples and Comparative Synthesis Examples, and acetoaceto-m-xylidide and acetoacetate contained in the tetrahydrofuran (THF) extract of the toners of Examples and Comparative Examples -O-
Toluidide, acetoaceto-o-anisidide, acetoaceto-2, 5'-dimethoxy-4-chloroanilide and m
-Xylidine, o-toluidine, o-anisidine, 2,
5′-Dimethoxy-4-chloroaniline was separated and quantified by high performance liquid chromatography, and the content thereof was determined. The results are shown in Table 1. The measurement was performed using an octadecylsilane-based filler, a 1: 1 mixture of methanol and water as an eluent, and a detection wavelength of 235 nm.

[Evaluation] A developer was prepared by mixing 4 parts of each yellow toner obtained in Examples 1 to 4 and Comparative Examples 1 to 3 with 96 parts of a carrier coated with a silicone-coated ferrite particle having an average particle diameter of 50 μm. Digital color copier (150
0.8 mg / each yellow toner
cm ² continuously on paper with a digital color copier
The odor at the time of copying 0 sheets was evaluated. The evaluation method and criteria are the same as those in the odor test 1. Table 2 shows the results. <Odor evaluation rank> O: Almost no odor is felt. Δ: Odor was slightly felt, but practically not a problem. ×: Anxious because of odor.

[0055]

[Table 1]

[0056]

[Table 2]

[0057]

According to the present invention, by reducing the content of amines in the yellow toner, it is possible to obtain a yellow toner for developing electrostatic images which is less likely to cause odor during use. Particularly, by using a disazo pigment having an average particle diameter of 0.3 μm or less and an aspect ratio of 3 or less, an electrostatic charge image which gives a clear image with no fog and good fog without impairing light transparency on an OHP sheet. A yellow toner for development can be obtained.

Claims (8)

[Claims] A disazo pigment (1) and at least a binder resin are melt-kneaded, and the amine content is 20 p.
pm or less, the yellow toner for developing an electrostatic image. 2. A disazo pigment obtained by subjecting a disazo pigment (1) to a coupling reaction between a tetrazo solution of benzidine and a coupler liquid containing a stoichiometric excess of acetoacetanilide with respect to the benzidine. A yellow toner for developing electrostatic images, comprising adding hypoiodite to the slurry, adjusting the pH to 5.5 or less, and treating excess acetoacetanilide with the precipitated iodine. 3. The disazo pigment (1) is prepared by treating an excess acetoacetanilide with precipitated iodine, adding a water-soluble inorganic salt and a water-soluble solvent without passing through a drying step, and kneading the mixture. 3. A yellow toner for developing electrostatic images according to claim 2, which is a treated disazo pigment (3) obtained by removing the inorganic salt and the water-soluble solvent. 4. The disazo pigment (1) is prepared by treating an excess of acetoacetanilides with precipitated iodine, passing through a drying step, adding a water-soluble inorganic salt and a water-soluble solvent, and kneading the mixture. The yellow toner for developing an electrostatic image according to claim 2, which is a treated disazo pigment (4) obtained by removing an inorganic salt and the water-soluble solvent. 5. After removing the water-soluble inorganic salt and the water-soluble solvent, a mixture of disazo pigment (3) or (4) and water is kneaded with a dispersing resin by heating and kneading to remove water.
The yellow toner for developing an electrostatic image according to claim 3, wherein the toner is melt-kneaded with a binder resin. 6. After removing the water-soluble inorganic salt and the water-soluble solvent, a mixture of disazo pigment (3) or (4) and water is heated and kneaded with a binder resin to remove water. The yellow toner for developing an electrostatic image according to claim 3 or 4, wherein 7. The method according to claim 3, wherein the water-soluble inorganic salt and the water-soluble solvent are removed, dried, and then heated and kneaded together with the disazo pigment (3) or (4) and the binder resin.
Or a yellow toner for developing an electrostatic image according to 4. 8. The disazo pigments (1) to (4) have an average particle size of 0.3 μm or less and a ratio of the major axis to the minor axis of the pigment particles is 3.0 or less. 8. The yellow toner for developing an electrostatic image according to any one of items 7 to 7.